In the wireless communication system, a base station refers to equipment which provides service for terminals, and the base station communicates with the terminals through an up/down link. Downlink or forward direction refers to the direction from the base station to the terminal, while uplink or backward direction refers to the direction from the terminal to the base station. Multiple terminals can simultaneously transmit data to the base station through an up link, and simultaneously receive data from the base station through a down link.
In a data transmission system which uses base station scheduling control, the scheduling allocation of all the resources of the system are usually carried out by the base station, for example, the resource allocation when the base station performs downlink transmission and the resources which can be used when the terminal performs uplink transmission are both scheduled and allocated by the base station.
In the OFDM system, the down links, used during downlink data transmission between the base station and different terminals in a same cell, are orthogonal with each other, such that internal inter-cell interference can be avoided. However, the down links among different cells may be not orthogonal, so each terminal may be subjected to downlink interference from the base station of other adjacent cells, viz. inter-cell interference.
To reduce the effect of inter-cell interference on system performance is an important goal of the design of a cellular system, as the inter-cell interference will reduce the system capacity, especially the transmission capability of users at the edge of the cell, and thereby affect the covering capability of the system and the performance of the terminal. In order to overcome the inter-cell interference, a solution of Adaptive Frequency Reuse (referred to as AFR) can be used to allocate different sub-band resources to the terminals, so as to reduce the intensity of inter-cell interference. FIG. 1 is a schematic diagram of an allocation method of frequency resources of adjacent sectors and restriction on transmission power of each sub-band. As shown in FIG. 1, the main principle of the Adaptive Frequency Reuse solution is: firstly, all the available frequency resources are divided into 7 sub-band sets: {right arrow over (W)}: [W1, W2, W3, W12, W23, W13, W123], wherein the frequency reuse factor of W1, W2, W3 is 3 (viz. Reuse 3, also referred to as Reuse 1/3, hereinafter referred to as Reuse 3), viz. the frequency resources in W1, W2, W3 are allocated to one of three adjacent sectors, and the other two sectors cannot use the frequency resources or need to employ a method of restricting the transmission power thereof in order to use the frequency resources, the reuse set of W1, W2, W3 is called as Reuse=3; the frequency reuse factor of W12, W23, W13 is 3/2, (viz. Reuse 3/2, also referred to as Reuse 2/3, hereinafter referred to as Reuse 3/2), viz. the frequency resources in W12, W23, W13 are allocated to two of three adjacent sectors, and the third sector cannot use the frequency resources or need to employ a method of restricting the transmission power thereof in order to use the frequency resources, the reuse set of W12, W23, W13 is called as Reuse=3/2; the frequency reuse factor of W123 is 1 (viz. Reuse 1), viz. three adjacent sectors all can use the frequency resources limitlessly, the reuse set of W123 is called as Reuse=1. Then, the base station allocates a cost (referred to as C) to each sub-band, viz. C=[C1, C2, C3, C12, C23, C13, C123]. Each terminal obtains Spectral Efficiency (referred to as SE) of each sub-band through channel estimation, and feeds back Channel Quality Information (referred to as CQI) values of M (M≧1) sub-bands having the largest nSEi to the base station by comparing the sizes of nSEi=SEi/Costi of each sub-band. Finally, the base station, according to CQI condition of sub-band reported by the terminal, performs resource allocation at the same time, self-adaptively adjusts the values of the cost of each sub-band, and notifies them to all the terminals in the cell.
In the above, the self-adaptive adjustment of cost value of each sub-band reflects the “cost” condition of different sub-bands in the cell, and the base station notifies the “cost” to all the terminals in the cell through the corresponding inter-cell interference control signaling. The terminals obtain the cost value of each sub-band by decoding the signaling, and further calculate nSEi to determine which sub-bands have the CQI values needed to be fed back to the base station. However, if the base station transmits the cost of all the sub-bands in the reuse set to the terminals, the system overhead will be increased.